Repeatability of Ultrasound-Defined Bladder Shape Metrics in Healthy Volunteers

Maddra, Kaitlyn M; Li, Rui; Nagle, Anna S.; Klausner, Adam P.; Speich, John E.

doi:10.2147/rru.s351347

Cited by 3 publications

(2 citation statements)

References 28 publications

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“…Previous work has used similar methods to identify bladder wall mechanical properties in humans in vivo using a combination of cystometry and ultrasound imaging (Dorr 1992 ; Maddra et al 2022 ). These studies highlight the value and importance that this new type of compliance measurement can have with regard to understanding urinary bladder function.…”

Section: Discussionmentioning

confidence: 99%

Quantifying whole bladder biomechanics using the novel pentaplanar reflected image macroscopy system

Hennig

Saxena

Broemer

et al. 2023

Biomech Model Mechanobiol

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Optimal bladder compliance is essential to urinary bladder storage and voiding functions. Calculated as the change in filling volume per change in pressure, bladder compliance is used clinically to characterize changes in bladder wall biomechanical properties that associate with lower urinary tract dysfunction. But because this method calculates compliance without regard to wall structure or wall volume, it gives little insight into the mechanical properties of the bladder wall during filling. Thus, we developed Pentaplanar Reflected Image Macroscopy (PRIM): a novel ex vivo imaging method to accurately calculate bladder wall stress and stretch in real time during bladder filling. The PRIM system simultaneously records intravesical pressure, infused volume, and an image of the bladder in five distinct visual planes. Wall thickness and volume were then measured and used to calculate stress and stretch during filling. As predicted, wall stress was nonlinear; only when intravesical pressure exceeded ~ 15 mmHg did bladder wall stress rapidly increase with respect to stretch. This method of calculating compliance as stress vs stretch also showed that the mechanical properties of the bladder wall remain similar in bladders of varying capacity. This study demonstrates how wall tension, stress and stretch can be measured, quantified, and used to accurately define bladder wall biomechanics in terms of actual material properties and not pressure/volume changes. This method is especially useful for determining how changes in bladder biomechanics are altered in pathologies where profound bladder wall remodeling occurs, such as diabetes and spinal cord injury.

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Section: Discussionmentioning

confidence: 99%

Quantifying whole bladder biomechanics using the novel pentaplanar reflected image macroscopy system

Hennig

Saxena

Broemer

et al. 2023

Biomech Model Mechanobiol

View full text Add to dashboard Cite

show abstract

“…Previous work has used similar methods to identify bladder wall mechanical properties in humans in vivo using a combination of cystometry and ultrasound imaging (Dorr 1992;Maddra et al 2022). These studies highlight the value and importance that this new type of compliance measurement can have with regard to understanding urinary bladder function.…”

Section: Discussionmentioning

confidence: 99%

Quantifying Whole Bladder Biomechanics Using the Novel Pentaplanar Reflected Image Macroscopy System

Hennig

Saxena

Broemer³

et al. 2022

Preprint

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Optimal bladder compliance is essential to urinary bladder storage and voiding functions. Calculated as the change in filling volume per change in pressure, bladder compliance is used clinically to characterize changes in bladder wall biomechanical properties that associate with lower urinary tract dysfunction. But because this method calculates compliance without regard to wall structure or wall volume, it gives little insight into the mechanical properties of the bladder wall during filling. Thus, we developed Pentaplanar Reflected Image Macroscopy (PRIM): a novel ex vivo imaging method to accurately calculate bladder wall stress and stretch in real time during bladder filling. The PRIM system simultaneously records intravesical pressure, infused volume, and an image of the bladder in 5 distinct visual planes. Wall thickness and volume were then measured and used to calculate stress and stretch during filling. As predicted, wall stress was nonlinear; only when intravesical pressure exceeded ~ 15 mmHg did bladder wall stress rapidly increase with respect to stretch. This method of calculating compliance as stress vs stretch also showed that the mechanical properties of the bladder wall remain similar in bladders of varying capacity. This study demonstrates how wall tension, stress and stretch can be measured, quantified, and used to accurately define bladder wall biomechanics in terms of actual material properties and not pressure/volume changes. This method is especially useful for determining how changes in bladder biomechanics are altered in pathologies where profound bladder wall remodeling occurs, such as diabetes and spinal cord injury.

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Use of statistical shape modeling to enhance the fluoroscopic evaluation of the bladder

Routzong¹,

Santiago‐Lastra²,

Gallo³

et al. 2022

Front. Urol.

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IntroductionVideo urodynamic studies (VUDS) use fluoroscopic imaging to visualize the bladder and multichannel urodynamics to assess its function. Qualitative assessment of bladder shape is used to identify abnormal features (e.g., diverticula) that correspond with pathophysiology; however, this assessment is limited in its ability to predict bladder function. Therefore, we developed a novel quantitative approach to assess bladder shape obtained from fluoroscopic VUDS images utilizing statistical shape modeling. This method was compared to existing binary and continuous shape quantification methods and used to identify relationships between bladder shape and measures of bladder physiology categorized as related to sensation, incontinence, or emptying.MethodsThis was a retrospective, cross-sectional study of 49 participants. Bladder walls were segmented from fluoroscopic images at rest with the bladder filled to approximately 300 mL. Bladder shape was evaluated in three ways: 1) binary categorization as typical or atypical based on clinical assessment, 2) quantification of height-to-width ratios, and 3) quantification by statistical shape modeling. Independent t-tests and correlations were used to assess associations between the three shape evaluation methods and to define relationships between shape and physiologic measures: 3 volumetric measures describing sensation, 2 dichotomous variables addressing incontinence, and 1 volumetric measure representing emptying.ResultsThe statistical shape model generated 5 modes of variation. Mode 1 corresponded with height-to-width ratio (r=0.920, p<0.001), modes 2 and 3 with diagonal height-to-width ratio (r=0.66 and -0.585, p<0.001 and <0.001), and mode 3 with binary shape categorization (p<0.001). In terms of function, those with atypical bladder shape had impaired emptying (p=0.010), modes 4 and 5 were significantly associated with measures of bladder sensation, mode 3 with urodynamic stress urinary incontinence, and mode 3 with emptying in those able to void (r=0.368, p=0.021). The relationship between mode 3 and emptying across all patients is best fitted by a quadratic function (p<0.001).DiscussionOur results demonstrate that binary shape categorization and bladder shape quantified by statistical shape modeling correspond with measures of bladder physiology. This foundational study establishes statistical shape modeling as a robust bladder shape quantification method that can be used to relate bladder shape with physiology.

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Repeatability of Ultrasound-Defined Bladder Shape Metrics in Healthy Volunteers

Cited by 3 publications

References 28 publications

Quantifying whole bladder biomechanics using the novel pentaplanar reflected image macroscopy system

Quantifying whole bladder biomechanics using the novel pentaplanar reflected image macroscopy system

Quantifying Whole Bladder Biomechanics Using the Novel Pentaplanar Reflected Image Macroscopy System

Use of statistical shape modeling to enhance the fluoroscopic evaluation of the bladder

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